Multi-rotor drone UAV ,how it works ,the working principle

Everyone knows that with the development of UAV drone technology in recent years, multi-rotor drone are becoming more and more popular because they are simple, stable, and safe to be used in many fields, such as police use,surveillance, environmental monitoring, and geographic mapping. , agriculture, fire protection, industrial testing, etc. What is the working principle of the multi-rotors drone? How does a multi-rotor drone work? Let us tell you below.

The basic theory of the rotor, people who have played bamboo poles should know: when the hand’s movement gives the bamboo pole a rotation speed, it will produce lift, let the bamboo pole take off.

In the same way, the multi-rotor drone (UAV) is also rotated by the motor, which causes the propeller to generate lift and fly. For example, a quadrotor drone, when the sum of the lifts of the four propellers of the aircraft is equal to the total weight of the aircraft, the lift of the aircraft is balanced with gravity, and the aircraft can hover in the air.

According to Newton’s third law, while the rotor is rotating, it also applies a reaction force (anti-torque) to the motor, causing the motor to rotate in the opposite direction. This is why today’s helicopters carry a “small tail” that exerts a force in the horizontal direction to counteract this reaction and keep the helicopter body stable.

Back to the multi-rotor drone, its propellers also generate such forces, so in order to avoid the crazy spin of the aircraft, the four propellers of the quadrotor rotate in opposite directions.

As shown in the figure below, the red arrow of the triangle indicates the orientation of the nose of the aircraft, the direction of rotation of the propellers M1 and M3 is counterclockwise, and the direction of rotation of the propellers M2 and M4 is clockwise.

When flying, the counterclockwise reaction force (anti-torque) generated by M2 and M4 cancels the clockwise reaction force (reverse torque) generated by M1 and M3, and the aircraft fuselage can remain stable. It will not be as crazy as Daxiong. “Rotate.”

Not only that, the front, rear, left and right or rotary flight of a multi-rotor drone is also achieved by the speed control of multiple propellers:

Vertical lift

This is well understood. When the drone needs to raise the altitude, the four propellers accelerate at the same time, the lift increases, and the drone rises. When the drone needs to reduce the height, the four propellers will reduce the speed at the same time, and the drone will drop.

The reason why it is emphasized at the same time is that it is very important to maintain the attitude of the aircraft body when maintaining the relative stability of the rotor speed. After reading it, you will understand it~

In situ rotation

As already mentioned above, when the motor speeds of the drones are the same, the counter torque of the aircraft is cancelled and no rotation occurs.

However, when the drone is to be rotated in situ, we can use this counter torque. The motor speeds of two clockwise rotations of M2 and M4 increase, and the speeds of two counterclockwise rotations of M1 and M3 decrease. Due to the anti-torque effect, The airplane will rotate counterclockwise.

Horizontal movement

Unlike a passenger aircraft that we usually ride, a multi-axle aircraft does not have a propeller that is perpendicular to the ground like a passenger plane, so it cannot directly generate horizontal forces to move horizontally.

Of course, this is hard to beat us. For the four-rotor of the figure, when it is necessary to follow the direction of the triangular arrow, the M3 and M4 motor propellers will increase the speed, while the M1 and M2 motor propellers will reduce the speed, due to the lift at the rear of the aircraft. Above the front of the aircraft, the attitude of the aircraft will tilt forward.

The side view when tilting is as shown in the following figure. At this time, the lift generated by the propeller has a component in the horizontal direction in addition to offsetting the gravity of the aircraft in the vertical direction. This component gives the aircraft a horizontal acceleration. It is therefore possible to fly forward.

Conversely: When the M1 and M2 motors accelerate and the M3 and M4 motors decelerate, the airplane will tilt backwards and fly backwards.

Similarly, when the M1 and M4 motors accelerate and the M2 and M3 motors decelerate, the airplane tilts to the left and thus flies to the left;

When the M2 and M3 motors accelerate and the M1 and M4 motors decelerate, the airplane tilts to the right and flies to the right.

In fact, before the multi-rotor, people used more complex fixed-wing aircraft and helicopters for aerial photography.

Although the helicopter is heavy and fast, its structure is very complicated and precise. Thousands of parts are very troublesome in terms of debugging and maintenance.

In contrast, the multi-rotor flight principle is simple, the fuselage structure is simpler and more reliable, and consumers can quickly get started.